1. Field of the Invention
The present invention is directed to a drive system, and more particularly to a selectable drive system for controlling the direction of an air propeller that drives an airboat.
2. Background Information
Drive systems for propelling airboats are known in the art. For example, U.S. Pat. No. 6,540,570 B1 issued to Eakin on Apr. 1, 2003. This reference illustrates an airboat where the engine is mounted high above the hull. A transmission is driven by the engine through a belt connection located between a drive shaft and a sprocket. A number of gears transmit power from the engine and rotate the air propellers.
Other examples of prior art airboat drive systems include:                (a) U.S. Pat. No. 5,839,926 issued to K-Way on Nov. 24, 1998,        (b) U.S. Pat. No. 6,053,782 issued to Bell on Apr. 25, 2000,        (c) U.S. Pat. No. 6,478,641 issued to Jordan on Nov. 12, 2002,        (d) U.S. Pat. No. 5,724,867 issued to Jordan on Mar. 10, 1998, and        (e) U.S. Pat. No. 6,299,485 issued to Jordan on Oct. 9, 2001.        
All of these references illustrate an engine mounted high above the hull of an airboat. A transmission is driven by a direct connection to the engine through a  drive shaft. A number of gears are provided to operate a pair of output drive shafts. One of the output drive shafts is hollow and surrounds the other solid drive shaft to rotate the air propellers. The transmissions are directly driven by the engine.
Another example of a prior art drive system is shown in the Husky™ Nattiq™ airboat (www.huskyairboats.com). This airboat has the engine mounted low in the hull of an airboat. The existing drive system is an elongated belt extending from a pulley mounted on an end of a drive shaft of an engine to another pulley mounted on a air propeller drive shaft.
However, there is a fundamental problem and limitation with the known prior art airboat drive systems. The transmissions are not selectable and do not provide a reverse capability. As a result, the prior art drives fail to provide thrust for maneuverability and control of an airboat.
Therefore, there is a need for an improved drive system in an airboat that is selectable between a forward, neutral, and reverse direction when the engine is running.